<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="../vue.js"></script>
    <style>
        .box {
            width: 100px;
            height: 100px;
            background-color: pink;
        }

        .newbox {
            width: 100px;
            height: 100px;
            background-color: lawngreen;
        }
    </style>
</head>

<body>
    <div id="app">
        <div>num:{{ num }}</div>
        <div :class="classname"></div>
        <button @click=fn(11)>点击num=11</button>
    </div>

    <script>
        var vm = new Vue({
            el: '#app',
            data: {
                num: 10,
                classname: 'box',
            },
            methods: {
                fn(b) {
                    // console.log(b);
                    //获取data中的属性值
                    console.log(this.num);//10
                    this.num =b;
                    this.classname = 'newbox'
                }
            }
        })
    </script>
</body>

</html>